Technical
Specification
IQ18-QTC Family
OUTPUT VOꢃTꢂGꢁ TRIM (Pin 6):ꢀTheꢀTRIMꢀinputꢀpermitsꢀtheꢀ
userꢀtoꢀadjustꢀtheꢀoutputꢀvoltageꢀacrossꢀtheꢀsenseꢀleadsꢀupꢀorꢀ
downꢀaccordingꢀtoꢀtheꢀtrimꢀrangeꢀspecifications.
PROTECTIONꢀFEATURES
Input Under-Voltage ꢃockout:ꢀ Theꢀ converterꢀ isꢀ designedꢀ
toꢀturnꢀoffꢀwhenꢀtheꢀinputꢀvoltageꢀisꢀtooꢀlow,ꢀhelpingꢀavoidꢀanꢀ
inputꢀsystemꢀinstabilityꢀproblem,ꢀdescribedꢀinꢀmoreꢀdetailꢀinꢀtheꢀ
applicationꢀnoteꢀtitledꢀ“0”ꢀonꢀourꢀwebsite.ꢀTheꢀlockoutꢀcircuitryꢀ
isꢀ aꢀ comparatorꢀ withꢀ dcꢀ hysteresis.ꢀ Whenꢀ theꢀ inputꢀ voltageꢀ isꢀ
rising,ꢀ itꢀ mustꢀ exceedꢀ theꢀ typicalꢀ Turn-Onꢀ Voltageꢀ Thresholdꢀ
valueꢀ (listedꢀ onꢀ theꢀ specificationsꢀ page)ꢀ beforeꢀ theꢀ converterꢀ
willꢀturnꢀon.ꢀOnceꢀtheꢀconverterꢀisꢀon,ꢀtheꢀinputꢀvoltageꢀmustꢀfallꢀ
belowꢀtheꢀtypicalꢀTurn-OffꢀVoltageꢀThresholdꢀvalueꢀbeforeꢀtheꢀ
converterꢀwillꢀturnꢀoff.
Toꢀ decreaseꢀ theꢀ outputꢀ voltage,ꢀ theꢀ userꢀ shouldꢀ connectꢀ aꢀ
resistorꢀbetweenꢀPinꢀ6ꢀandꢀPinꢀ5ꢀ(SENSE(-)ꢀinput).ꢀForꢀaꢀdesiredꢀ
decreaseꢀofꢀtheꢀnominalꢀoutputꢀvoltage,ꢀtheꢀvalueꢀofꢀtheꢀresistorꢀ
shouldꢀbe
ꢀ 511
ꢀꢀ
-ꢀ10.22 (kW)
R
ꢀ=
trim-down
(∆%)
where
ꢀ
ꢀ Vnominalꢀ–ꢀVdesired ꢀ
ꢀꢀꢀꢀꢀꢀVnominal
Output Current ꢃimit:ꢀ Theꢀ maximumꢀ currentꢀ limitꢀ remainsꢀ
constantꢀ asꢀ theꢀ outputꢀ voltageꢀ drops.ꢀ However,ꢀ onceꢀ theꢀ
impedanceꢀofꢀtheꢀloadꢀacrossꢀtheꢀoutputꢀisꢀsmallꢀenoughꢀtoꢀmakeꢀ
theꢀoutputꢀvoltageꢀdropꢀbelowꢀtheꢀspecifiedꢀOutputꢀDCꢀCurrent-
LimitꢀShutdownꢀVoltage,ꢀtheꢀconverterꢀturnsꢀoff.
=
xꢀ100%
∆%
ꢀ
ꢀ
ꢀ
Toꢀ increaseꢀ theꢀ outputꢀ voltage,ꢀ theꢀ userꢀ shouldꢀ connectꢀ aꢀ
resistorꢀbetweenꢀPinꢀ6ꢀandꢀPinꢀ7ꢀ(SENSE(+)ꢀinput).ꢀForꢀaꢀdesiredꢀ
increaseꢀofꢀtheꢀnominalꢀoutputꢀvoltage,ꢀtheꢀvalueꢀofꢀtheꢀresistorꢀ
shouldꢀbeꢀ
Theꢀconverterꢀthenꢀentersꢀaꢀ“hiccupꢀmode”ꢀwhereꢀitꢀrepeatedlyꢀ
turnsꢀonꢀandꢀoffꢀatꢀaꢀ5ꢀHzꢀ(nominal)ꢀfrequencyꢀwithꢀaꢀ5%ꢀdutyꢀ
cycleꢀuntilꢀtheꢀshortꢀcircuitꢀconditionꢀisꢀremoved.ꢀThisꢀpreventsꢀ
excessiveꢀheatingꢀofꢀtheꢀconverterꢀorꢀtheꢀloadꢀboard.
5.11VOUTꢀ ꢀ(100+∆%)
x
511
ꢀꢀ
_
_ꢀ
R
=ꢀ
(kW)
trim-up
10.22
)
(
1.225∆%
∆%
Output Over-Voltage ꢃimit:ꢀIfꢀtheꢀvoltageꢀacrossꢀtheꢀoutputꢀ
pinsꢀexceedsꢀtheꢀOutputꢀOver-VoltageꢀProtectionꢀthreshold,ꢀtheꢀ
converterꢀwillꢀimmediatelyꢀstopꢀswitching.ꢀThisꢀpreventsꢀdamageꢀ
toꢀtheꢀloadꢀcircuitꢀdueꢀtoꢀ1)ꢀexcessiveꢀseriesꢀresistanceꢀinꢀoutputꢀ
currentꢀ pathꢀ fromꢀ converterꢀ outputꢀ pinsꢀ toꢀ senseꢀ point,ꢀ 2)ꢀ aꢀ
releaseꢀofꢀaꢀshort-circuitꢀcondition,ꢀorꢀ3)ꢀaꢀreleaseꢀofꢀaꢀcurrentꢀ
limitꢀ condition.ꢀ Loadꢀ capacitanceꢀ determinesꢀ exactlyꢀ howꢀ highꢀ
theꢀoutputꢀvoltageꢀwillꢀriseꢀinꢀresponseꢀtoꢀtheseꢀconditions.ꢀAfterꢀ
200ꢀmsꢀtheꢀconverterꢀwillꢀautomaticallyꢀrestart.
where
V
ꢀ=ꢀNominalꢀOutputꢀVoltage
out
Graphsꢀ onꢀ Pageꢀ 3ꢀ showꢀ theꢀ relationshipꢀ betweenꢀ theꢀ trimꢀ
resistorꢀvalueꢀandꢀRtrim-upꢀandꢀRtrim-down,ꢀshowingꢀtheꢀtotalꢀ
rangeꢀtheꢀoutputꢀvoltageꢀcanꢀbeꢀtrimmedꢀupꢀorꢀdown.
Note:ꢀtheꢀTRIMꢀfeatureꢀdoesꢀnotꢀaffectꢀtheꢀvoltageꢀatꢀwhichꢀtheꢀ
outputꢀover-voltageꢀprotectionꢀcircuitꢀisꢀtriggered.ꢀTrimmingꢀtheꢀ
outputꢀvoltageꢀtooꢀhighꢀmayꢀcauseꢀtheꢀover-voltageꢀprotectionꢀ
circuitꢀtoꢀengage,ꢀparticularlyꢀduringꢀtransients.
Over-Temperature Shutdown:ꢀ Aꢀ temperatureꢀ sensorꢀ onꢀ
theꢀ converterꢀ sensesꢀ theꢀ averageꢀ temperatureꢀ ofꢀ theꢀ module.ꢀ
Theꢀthermalꢀshutdownꢀcircuitꢀisꢀdesignedꢀtoꢀturnꢀtheꢀconverterꢀ
offꢀ whenꢀ theꢀ temperatureꢀ atꢀ theꢀ sensedꢀ locationꢀ reachesꢀ theꢀ
Over-Temperatureꢀ Shutdownꢀ value.ꢀ Itꢀ willꢀ allowꢀ theꢀ converterꢀ
toꢀturnꢀonꢀagainꢀwhenꢀtheꢀtemperatureꢀofꢀtheꢀsensedꢀlocationꢀ
fallsꢀbyꢀtheꢀamountꢀofꢀtheꢀOver-TemperatureꢀShutdownꢀRestartꢀ
Hysteresisꢀvalue.
ItꢀisꢀnotꢀnecessaryꢀforꢀtheꢀuserꢀtoꢀaddꢀcapacitanceꢀatꢀtheꢀTrimꢀ
pin.ꢀTheꢀnodeꢀisꢀinternallyꢀbypassedꢀtoꢀeliminateꢀnoise.
Total DC Variation of V
specifications,ꢀtheꢀmaximumꢀvariationꢀofꢀtheꢀdcꢀvalueꢀofꢀV
toꢀbothꢀtrimmingꢀandꢀremoteꢀloadꢀvoltageꢀdrops,ꢀshouldꢀnotꢀbeꢀ
:ꢀForꢀtheꢀconverterꢀtoꢀmeetꢀitsꢀfullꢀ
OUT
,ꢀdueꢀ
OUT
greaterꢀthanꢀthatꢀspecifiedꢀforꢀtheꢀoutputꢀvoltageꢀtrimꢀrange.
Product # IQ18xxxQTCxx
Phone 1-888-567-9596
www.synqor.com
Doc.# 005-IQ18QTX Rev. B
09/23/08
Page 25
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